The present application relates to semiconductor manufacturing. More particularly, the present application relates to a method of removing a material portion of a base substrate utilizing a controlled spalling process in which a handle substrate is used that contains metallization regions. The present application also relates to a structure that can be formed from such a method.
Devices such as, for example, photovoltaic and electro-optical, that can be produced in thin-film form have three clear advantages over their bulk counterparts. First, by virtue of less material used, thin-film devices ameliorate the materials cost associated with device production. Second, low device weight is a definite advantage that motivates industrial-level effort for a wide range of thin-film applications. Third, if dimensions are small enough, devices can exhibit mechanical flexibility in their thin-film form. Furthermore, if a device layer is removed from a substrate that can be reused, additional fabrication cost reduction can be achieved.
Efforts to (i) create thin-film substrates from bulk materials (i.e., semiconductors) and (ii) form thin-film device layers by removing device layers from the underlying bulk substrates on which they were formed are ongoing. The recent development, see, for example, U.S. Patent Application Publication No. 2010/0311250 A1 to Bedell et al., of a novel layer transfer method referred to as ‘controlled spalling technology’ has permitted the fabrication of low-cost, thin-film, high quality substrates by removing a surface layer from a base substrate. The thin-film substrate layers that can be removed by this controlled spalling technology can be used to 1) increase the cost per Watt value of conventional photovoltaic technology or 2) permit fabrication of novel, high-efficiency photovoltaic, electronic and opto-electronic materials that are flexible and can be used to produce new products.
Recent advancements in the area of high-efficiency, lightweight, flexible photovoltaic (PV) devices has opened the door to a new class of solar energy products. The controlled spalling process mentioned above can be used for transferring thin layers of III-V compound semiconductor materials from a rigid host substrate to a lightweight flexible substrate.
When multiple PV devices are integrated into a single flexible substrate, it is important that the electrical connections that link these devices do not deleteriously affect the performance of the multi-device module. In early prototypes of these flexible modules, it was found that high series resistance resulting from the use of commercially available flexible conductors (such as, for example, Ag-based inks) severely limited the performance of the module. As such, there is a need to provide a PV module design that can maximize mechanical flexibility, minimize weight and allow for low electrical resistance contact between adjacent PV devices.